The proposed work involves the synthesis of a lot of additivefree polytetramethylene (PTMO), 4, 4 diphenylmethane diisothionate (MDI), and polyurethaneurea (PUU). They will study bulk and surface characterization, and fabrication into tubes and sheets. Pilots quantity material goals have been identified. Fabrication details are provides. Sterile, packages samples of the polyurethaneurea will be characterized to determine the effect of gamma radiation and to assess time dependent surface changes in the polyurethaneurea primary reference materials. These studies are aimed at determining the effect of degradation by the gamma irradiation sterilization technique. In addition, the investigators will also address timedependent changes that might occur during storage prior to application.